1. Field of the Invention
The present invention relates to an articulated structure for a multi-axis robot having at least three degrees of freedom, and also to a multi-axis robot including such a structure.
2. Description of the Related Art
In the field of multi-axis robots, it is sometimes necessary to manipulate parts quickly along paths that are close to a plane. This applies for example when taking a part that is moving on a conveyor belt and placing it on a plane conditioning member. SCARA type robots are adapted to working in a horizontal plane. It is sometimes appropriate for these robots to be capable also of performing movements in a vertical plane. In such robots, vertical movement is generally provided by a ball-screw system located close to the tool, i.e. at the end of the articulated structure commonly referred to as the robot arm. This gives rise to a large amount of inertia for this articulated structure, thereby limiting the speed at which the tool can be moved. Furthermore, the size of the ball-screw system can be an impediment under certain conditions of use.
JP-A-59-146774 discloses an articulated structure in which the forearm comprises two plates having two connecting rods hinged between them to form a parallelogram structure, thus enabling the tool to be moved vertically by means of an actuator mounted on the forearm. That motor increases the inertia of the forearm, thereby limiting the speeds with which the tool can be moved.